Abstract
Heat shock proteins (Hsps) are stress-responsive molecular chaperones, which uphold proper protein folding in response to external and internal stresses. The Hsp100 gene family plays a substantial role in thermos-tolerance of plants. This study investigated evolutionary relationship and expression of ClpB/Hsp100 gene family in tomato under heat stress. Six SlHsp100 genes were identified using bioinformatics tools. In silico sub-cellular localization indicated that of these 6 ClpB/Hsp100 members, 4 are found in chloroplast, 1 in mitochondria and 1 in the cytoplasm. For evolutionary study, 36 SlHsp100 genes were included in the phylogenetic tree showing a hierarchical clustering shared by the members of the kingdoms Plantae, Archaea, Chromista, Fungi and Bacteria. A total 4 pairs of orthologous and 5 pairs of paralogous genes were identified. Functional divergence between different Hsp100 clusters showed considerable functional homology. Thermo-tolerance measured in terms of cell viability, cell membrane stability and pollen viability indicated that it was paralleled by thermal resistance of Hsps. Reverse transcriptase polymerase chain reaction was used to analyze gene expression in leaves of five-week-old tomato seedlings following exposure to heat stress (45°C) and control (25°C). Chloroplastic LeHSP110/ClpB gene was upregulated in all tomato genotypes after exposure to heat stress highlighting the crucial role of this gene family in acquired thermo-tolerance.
Highlights
Rising temperature is the most evident outcome of global climate changes
Chloroplastic LeHSP110/ClpB gene was upregulated in all tomato genotypes after exposure to heat stress highlighting the crucial role of this gene family in acquired thermo-tolerance
Our work provides a foundation to the understanding of functional divergence and evolution of Hsp100 gene family in tomato
Summary
Rising temperature is the most evident outcome of global climate changes. The increasing temperature sets up a tight corner for sustainable crop production. Heat stress posed by the rising temperature is a major limiting factor for crop production in tropical and subtropical regions of the world. An array of processes, including plant growth, physiology, development, yield and quality are significantly affected by heat stress [1]. Cellular injury and cell death may occur within a short time after exposure to high temperature. Increased fluidity of membrane are associated with high temperature stress, while moderate heat stress inactivates chloroplastic and mitochondrial enzymes, degrades proteins and negatively affects membrane integrity [2]
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